Youtube playback horrendous on AMD E-450 APU (no HW acceleration)

I've had same problem with older Firefox versions and they fixed it. But now that I've switched to Opera again, this thing is again happening to me. Youtube is stuttering and lagging like insane on this APU (CPU+GPU) even though the GPU is capable of decoding even 4K H.264. But stutters like crazy on 480p Youtube video because HW acceleration is f**ked up. Who do I need to poke to get this sorted out?

I know it's an old APU, but it's sole purpose in that laptop is internet browsing and Youtube. It used to handle that fine, but not anymore because everyone managed to break HW acceleration for it.